excerpted from an anxiety forum :
Behaving in an overly apprehensive manner creates the physiological, psychological, and emotional state of anxiety. Anxiety activates the stress response, which stresses the body. A body that becomes overly stressed can exhibit symptoms of stress.
So anxiety symptoms are actually symptoms of stress. They are called anxiety symptoms because behaving apprehensively is the main source of the stress that overly stresses the body, which then, causes the body to exhibit symptoms.